There are a number of technologies for producing alcohols, acids and C1-4 alkyl ethers of C6-10 alkanes from butadiene Dow, Shell, Kuraray and Oxeno have all been developing such process for a number of years.
There are a number of papers in the name of Pines dealing with the cracking of alcohols to alkenes over alumina. A desired product was an alpha olefin and the olefin tended to undergo internal isomerization to product a mixture of products including lower amounts of the alpha olefin and higher amounts of the internal olefin. Pines discovered that doping the alumina with a base tended to reduce the amount of isomerization leading to internal olefins. (Herman Pines and C. N. Pillai, JACS., 1961, 83 (15) 3270-3274; Herman Pines and C. N. Pillai, JACS., 1960, 82 (9) 2401-2402; Herman Pines and Werner O. Haag, JACS., 1960, 2471-2482; and Herman Pines and Werner O. Haag, JACS., 1961, 2847-2852. This art teaches away from the subject matter of the present invention as it requires the alumina be doped with small amounts an alkali or alkaline earth metal.
DE 3 915 493 issued to Metalgesellschaft A. G., and Godrej Sops Ltd., India teaches cracking a fatty alcohol plus 300 ppm of ammonia over alumina to product a olefin. The patent teaches away from the subject matter of the present invention as it requires the presence of a base which is used as a carrier gas.
U.S. Pat. No. 4,234,752 issued Nov. 18, 1980 to Wu et al., assigned to Phillips Petroleum Company teaches cracking alcohols to olefins over alkali (KOH) treated γ-alumina. The reference teaches away from the subject matter of the present invention as it teaches the alumina has to be doped with an alkali.
Canadian Patent 2,097,297 (corresponding to WO 92/10450) issued Nov. 7, 2000 to Bohley et al., assigned to the Dow Chemicals Company discloses and claims a process for preparing 1-octene by telomerizing 1,3-butadiene in the presence of a tertiary phosphine and a telomerization catalyst to product a 1-substituted 2,7-octadiene which is subsequently hydrogenated to a 1-substituted to octane which is cracked to 1-octene over alumina which may be modified. In the only example 1 methoxyoctane is passed over γ-alumina to produce 1-octene. The conversion was 80% and the selectivity to octenes (all octenes) was 66% at 330° C. There is no teaching in the reference as to pore size of the γ-alumina. The present invention achieves a greater selectivity to octenes. The reference gives no teaching or suggestion that the 1 substituted octane conversion could be increased by selecting a γ-alumina having a selected pore size.
WO 2004/052809 published Jun. 24, 2004 in the name of Kaizik et al., assigned to Oxeno Olefinchemie GMBH discloses cracking a 1-alkyl ether of octane over an alkali doped aluminum oxide. The present invention has eliminated an essential feature of this prior art, namely the doping with an alkali.
United States Patent Application 2003/0065233 A1 published Apr. 23, 2003 in the name of Fuji et al., assigned to Kuraray Co., Ltd. teaches a process for cracking a primary alcohol or ether to a 1-olefin in the presence of an alumina catalyst and an amine. The present invention has eliminated the required amine of the reference.
WO 2004/078336 A2 published Sep. 16, 2004 in the name of Ziehe et al., assigned to Sasol Germany GMBH teaches cracking (dehydration) a 1-alcohol to an alpha olefin over a γ-alumina having a pore volume greater than 0.9 cc/g, and a bimodal pore radii distribution such that there is at least one maximum in the mesopore size in the range from 30 to 80 Å (0.003 to 0.008 microns or micrometers) and one maximum in the macropore range greater than 1,000 Å (0.1 microns or micrometers) and the macropores make up more than 40% of the total pore volume. Preferably the alcohol is passed over the catalyst together with a carrier gas. The reference does not teach or suggest the process could be used with an ether. The present invention has eliminated the carrier gas. Further the present invention is directed to alumina having a pore volume not less than 1.1 cc/g.
The present invention seeks to provide a simple process for cracking lower ethers of C6-10 alkanes to 1-C6-10 olefins at a conversion not less than 70% and a WHSV from 8 to 20 hr−1 in the presence of a γ-alumina which has not been treated with a base and has a pore volume of at least 1.0 cc/g, preferably 1.1 cc/g and an average pore diameter of greater than 150 Å, preferably greater than 190 Å and most preferably more than 200 Å.